Removal of ectoparasites

ABSTRACT

Ectoparasites, such as fleas, ticks, mites and lice, are removed from a human or animal host after applying a composition to the affected area that causes desiccation of the organism. In one embodiment, treatment is effected by applying a substantially anhydrous composition that has a strong affinity for water. As the composition hydrates, it desiccates the pests and facilitates their mechanical removal, such as by combing.

[0001] The present invention relates generally to the removal ofectoparasites from the bodies of humans and animals, and moreparticularly to a topical treatment to facilitate such removal.

[0002] Ectoparasitic infestation of humans and animals is a serioushealth problem throughout the world. Of particular importance as apublic health issue is pediculosis, or infestations with lice, which arepervasive among children and can quickly be spread in a school setting.A very common parasite is Pediculus humanus var capitis, the common headlouse, although there are other important parasites, including Pthiruspubis (the pubic louse) and Pediculus humanus var corporis (the bodylouse). Infestations are frequently accompanied by itching and skindamage. Infections may occur when the skin is scratched in an attempt torelieve the itching. Further, lice are known to be capable oftransmitting serious diseases, including trench fever, relapsing feverand typhus.

[0003] Pediculosis is most frequently treated by applying pesticidalcompositions, such as lotions or shampoos, to the affected body areas,such as the hair, and then exhaustively combing with a fine-toothed combmade especially for the purpose of removing nits. Commercially availablepreparations may include as their active ingredients pyrethrins,piperonyl butoxide, malathion, lindane or permethrins, many of whichunfortunately have neurotoxic properties, are readily absorbed throughthe skin and therefore can establish undesirable systemicconcentrations. It is perceived that the effectiveness of pesticides hasrecently diminished, as the parasites appear to continually become moreresistant to their action. The resistance may be aggravated by smallamounts of residual pesticide on the treated areas, following theprocedure. This resistance also contributes to an increased opportunityfor toxic systemic exposure to the active ingredients, since thepreparations must be applied repeatedly to obtain an eradication of theinfestation. Further, the pesticides do not usually kill the parasite'seggs that may be present on a host, so the tedious mechanical removaltechniques must also be used.

[0004] DiNapoli et al., “Eradication of Head Lice with a SingleTreatment,” American Journal of Public Health, Vol. 78, pages 978-980,1988, reported a study in which 7 percent of patients treated with acommercial 1 percent permethrin cream rinse, and 16 percent of patientstreated with a commercial product containing 0.3 percent pyrethrins, 3percent piperonyl butoxide, 1.2 percent petroleum distillate and 2.4percent benzyl alcohol, experienced adverse reactions includingpruritis, erythema, tingling, rash and other conditions. Further, by 14days following treatment 38 percent of the patients treated with thepyrethrin product were found to host live lice, considered a treatmentfailure. Permethrin is described as having residual activity on the hairfor up to two weeks.

[0005] R. J. Roberts et al., “Comparison of Wet Combing with Malathionfor Treatment of Head Lice in the UK: a Pragmatic Randomised ControlledTrial,” The Lancet, Vol. 356, pages 540-544, 2000, report thatmechanical removal of lice with a commercial comb every 3-4 days for twoweeks gave a “cure” rate of only 38 percent, while two treatments with0.5 percent malathion lotion seven days apart gave a “cure” rate of 78percent.

[0006] Published results for the various topical pesticidal treatmentswere compared by. R. H. Vander Stichele et al., “Systematic Review ofClinical Efficacy of Topical Treatments for Head Lice,” British MedicalJournal, Vol. 311, pages 604-608, 1995. It was concluded that onlypermethrin had sufficient evidence of efficacy.

[0007] There are other approaches to treating the infestations,including the application of heavy, oily substances such as mineral oil,petrolatum, mayonnaise and the like in an attempt to suffocate theectoparasites, but these have not been found particularly effective,esthetically pleasing or convenient. One major disadvantage of suchtreatments is the prolonged time (usually several hours) required toachieve suffocation, after the agent has been applied.

[0008] The suffocation technique has been refined, such as by theapproach of U.S. Pat. No 6,139,859 to Precopio which utilizesair-impermeable water-dispersible liquid compositions containing surfaceactive agents. Another type of treatment refinement is the technique ofPearlman et al. in PCT International Publication WO 99/18800, involvingthe topical application of surfactant substances as “pediculostaticagents” which immobilize the parasites to permit their removal bycombing.

[0009] It remains desirable to have a treatment for ectoparasiticinfestations which is efficacious, acts rapidly and does not generategreat discomfort or require any exposure of the host to toxic agents.

SUMMARY OF THE INVENTION

[0010] The present invention is a treatment for ectoparasiticinfestations, particularly those involving fleas, ticks, mites or lice,comprising establishing environmental conditions whereby systemicmoisture is removed from the ectoparasites, for a time sufficient tocause immobilization or death of the ectoparasites, then removing thepests by mechanical means such as combing.

[0011] This invention involves topical applications of compositionscontaining active ingredients which have a strong affinity for water,such as is present in organisms such as ectoparasites. Contact of theorganisms with the active agents causes desiccation which results inimmobilization and/or mortality of the parasites, facilitating theirmechanical removal by combing and other techniques. In many instances,the active agents also change the microenvironmental pH conditions; thiscan also have a significant adverse effect on mobility of the organismsand viability of their eggs.

[0012] Treatment of ectoparasites can be conducted using a compositionwhich generates a strong hydration reaction, when contacted with water.In one embodiment, the composition is a particulate solid, a semi-solidor a fluid containing substantially no aqueous matter, or in someinstances only a small amount of water, and which contains a particulateinorganic substance that undergoes a strong hydration reaction in thepresence of water. Examples of suitable substances are salts of alkalimetals and alkaline earth metals. The hydration reaction is notnecessarily one which results in formation of any new chemical compound,but can be an absorption-type reaction, and may be exothermic,endothermic or not involve any significant temperature changes.

DETAILED DESCRIPTION OF THE INVENTION

[0013] The invention will be described primarily as it relates to thereduction of human head lice infestations, although those skilled in theart will recognize its applicability to other ectoparasites and animalsubjects, and the inventors intend that their invention will have suchapplicability.

[0014] In the following description and the claims, it is intended thata reference to a percentage means percent by weight, unless the contextclearly indicates otherwise. Since the chemical names for certaincomposition ingredients are quite cumbersome, some ingredients areidentified herein by their adopted names as given in standard referenceworks, including J. A. Wenninger et al, Eds., International CosmeticIngredient Dictionary and Handbook; 8^(th) Ed., The Cosmetic, Toiletryand Fragrance Association, Washington, D.C., 1999.

[0015] Lice egg cases (“nits”) are thought to be attached to hair bymeans of mucopolysaccharide adhesive substances. Removal of the nitstherefore requires a very thorough combing operation, and is notappreciably facilitated by many of the usual pesticide treatments.However, embodiments of the present invention provide both desiccationand a changed pH in the microenvironment of the nit, which can alter thephysical and chemical nature of the egg casing itself. The provision oflubricious agents in a composition also can facilitate lice and nitremoval by combing.

[0016] Suitable active agents for use in the present invention aregenerally those salts of alkali metals, ammonium ions, alkaline earthmetals and transition metals that have a strong affinity for water.Examples of useful substances include one or more of lithium chloride,sodium chloride, sodium nitrate, sodium sulfate, potassium chloride,potassium nitrate, potassium sulfate, ammonium chloride, ammoniumnitrate, magnesium chloride, magnesium nitrate, calcium chloride,calcium bromide, calcium nitrate, calcium sulfate, strontium chloride,strontium nitrate and zinc chloride. This listing is not intended to beexhaustive, as many other substances can be used. The compounds will beused in their anhydrous or substantially anhydrous forms, and mixturesof any two or more active agents can be used.

[0017] When an active ingredient is placed in contact with water, suchas that contained in moistened hair, in the immediate vicinity of anectoparasite or the egg of an ectoparasite, a desiccatingmicroenvironment is created. Depending on the chemical nature of theactive ingredient, there may also be a change in pH and/or a localizedchange in temperature. All of these environmental changes aredetrimental to the viability of the ectoparasite and its eggs. Theresult will ideally be death of the ectoparasite and eggs, but in someinstances inhibition of the mobility of the pest will be the primaryeffect. In any event, it will typically be necessary to remove the deadand immobilized organisms, and the eggs, by combing or other mechanicalmeans.

[0018] In its least complicated embodiment, a desiccating compositionfor ectoparasite removal can contain only a solid particulate activeingredient or mixture of active ingredients, preferably in the form offinely divided particles. However, in many instances it will be desiredto include other components, such as up to about 50 percent of inactiveparticulate fillers, diluents or extenders, such as talc, cornstarch andthe like, to promote more uniform coverage of the area to which thecomposition is applied. These dry compositions can also include solidsurfactants, so that the product can be easily removed following atreatment by merely adding water to form a cleansing environment (suchas a shampoo) and then rinsing the treated area with additional water.

[0019] More typically, the composition will be fluid, such as in theform of a suspension or lotion containing about 1 to about 50 percent ofthe active ingredient or mixture of active ingredients, since suchproduct forms are generally more easily applied.

[0020] Useful fluid desiccating compositions can be prepared bysuspending, or in some instances dissolving, an active ingredient ormixture of active ingredients in a substantially anhydrous liquidvehicle such as: a hydrocarbon, including light and heavy mineral oils;a glycol such as a polyethylene glycol, propylene glycol or triethyleneglycol; glycerol; and the like. Use of the glycols is presentlypreferred, since they can also act as desiccating agents. Typicalconcentrations of the vehicle range from about 1 to about 60 percent.

[0021] Optionally, a suspending agent may be present in a fluiddesiccating composition to maintain a stable dispersion. Useful agentsinclude, without limitation, fumed silica and polyvinylpyrrolidonehaving molecular weights from about 25,000 to about 100,000, in amountsabout 0.1 to about 2 percent.

[0022] The compositions may further include other components, such assurfactants, lubricants, texture modifiers, acidifiers and/orpreservatives.

[0023] Useful optional surfactants include, without limitation, sodiumlauryl sulfate, sorbitan laurate, mixtures of glyceryl stearate andPEG-100 stearate, methyl gluceth-10, methyl gluceth-40, sorbitanpalmitate, polysorbate 20, polysorbate 80, steareth-2 and many others.The surfactants will be present in amounts about 0.1 to about 16percent, and can create shampoo-type products which are easily removedafter the ectoparasite treatment is completed.

[0024] The lubricants that can be incorporated are represented bydimethicone, simethicone and other silicone-type materials, and act tolubricate and condition the hair, as well as facilitate passage of acomb through the hair. Useful concentrations, when this component ispresent, are about 0.1 to about 2 percent.

[0025] Optional texture modifiers that may be included are exemplifiedby stearic acid, cetyl alcohol, PEG-180, polyethylene glycol 1450 andpolyethylene glycol 3350, in amounts about 0.1 percent to about 5percent.

[0026] It may be desired to incorporate a pH-adjusting ingredient in thecomposition, if the hydrated active ingredient tends to establishexcessively acidic or alkaline conditions (such as pH values which areless than about 4 or greater than about 9). Optional acidifiers that maybe used include, without limitation, benzoic acid, citric acid andstearic acid. Useful optional alkalizers include, without limitation,calcium hydroxide, magnesium hydroxide and organic bases such astriethanolamine. The pH adjusters, when used, will generally be presentin amounts about 0.1 percent to about 2 percent, as needed to obtain adesired bulk pH condition.

[0027] As an alternative to incorporating a pH adjusting ingredient,suitable bulk pH conditions can frequently be obtained by incorporatingan active ingredient that yields acidic conditions together with anotheractive ingredient which yields alkaline conditions.

[0028] Products that are intended for application to the skin frequentlyare protected against microbial proliferation by the inclusion of apreservative component. Suitable preservatives for use in the presentcompositions include, without limitation, methylparaben, propylparabenand benzethonium chloride. The preservative, when present, willtypically be included in concentrations about 0.05 to about 0.2 percent.

[0029] Included within the scope of the present invention is a kit fortreating an ectoparasite infestation, including a suitable containerfilled with a composition that can be applied to an area of the body tocause desiccation of ectoparasites, together with a mechanical devicefor removing ectoparasites after they are affected by the composition.For compositions that are in the form of a fluid, such as liquids,lotions and creams, the composition can be contained in a bottle orcollapsible tube. Aerosol compositions can be contained in the customarydispensing canisters, fitted with a suitable valve for dispensing theproduct. Powdered compositions can be contained in one of the customarycanisters having a perforated cap for shaking out a desired amount, orin a bottle. Many delousing combs are commercially available, beingfabricated from plastic substances or metals, and any of these aresuitable for inclusion in the kit. It is preferred that the kit be madesuitable for a single use, including sufficient composition for oneapplication.

[0030] The invention will be further described with reference to thefollowing example, which is not intended to limit the scope of theclaimed invention in any manner.

EXAMPLE

[0031] A lotion composition for ectoparasite removal is prepared bycombining the following components: Ingredient Percent Calcium sulfate,anhydrous 20 Benzoic acid 2 Fumed silica 0.3 Cetyl alcohol 1.5Polyvinylpyrrolidone 0.5 Cyclomethicone + Dimethicone copolyol* 2Methylparaben 0.13 Polyethylene glycol 67 Propylparaben 0.07 Polysorbate20 5 Stearic acid 1.5

[0032] From this description of specific embodiments of the invention,it will be appreciated that the present invention is not limited tothose precise embodiments and that various changes and modifications canbe effected therein by one of ordinary skill in the art, withoutdeparting from the scope or spirit of the invention as defined solely bythe appended claims.

What is claimed is:
 1. A method for treating an ectoparasiticinfestation of an area of a human or animal body, comprisingestablishing a desiccating environment in the area which causesectoparasites to become immobile or killed and then removing theectoparasites from the area.
 2. The method of claim 1, wherein theectoparasites comprise Pediculus humanus var capitis.
 3. The method ofclaim 1, wherein the ectoparasites comprise Pediculus humanus varcorporis.
 4. The method of claim 1, wherein the ectoparasites comprisePediculus humanus var pubis.
 5. The method of claim 1, wherein theectoparasites comprise fleas, ticks or mites.
 6. The method of claim 1,wherein desiccating conditions are established by applying to the area acomposition having a strong affinity for water.
 7. The method of claim1, wherein desiccating conditions are established by applying to thearea a composition comprising a substantially anhydrous inorganic salt.8. The method of claim 1, wherein desiccating conditions are establishedby applying to the area a composition comprising one or moresubstantially anhydrous salts selected from the group consisting oflithium chloride, sodium chloride, sodium nitrate, sodium sulfate,potassium chloride, potassium nitrate, potassium sulfate, ammoniumchloride, ammonium nitrate, magnesium chloride, magnesium nitrate,calcium chloride, calcium bromide, calcium nitrate, calcium sulfate,strontium chloride, strontium nitrate and zinc chloride.
 9. The methodof claim 1, wherein the composition is in the form of a powder.
 10. Themethod of claim 1, wherein the composition is in the form of asemi-solid or fluid.
 11. The method of claim 1, wherein immobilized orkilled ectoparasites are removed by combing.
 12. A substantiallyanhydrous composition comprising a particulate water-soluble inorganicsubstance which has a strong affinity for water, the inorganic substancebeing present in a concentration sufficient to desiccate ectoparasitesand cause the ectoparasites to become immobile or killed, when thecomposition is applied to an area of the body of an animal or human. 13.The composition of claim 12, wherein the inorganic substance comprisesone or more members selected from the group consisting of lithiumchloride, sodium chloride, sodium nitrate, sodium sulfate, potassiumchloride, potassium nitrate, potassium sulfate, ammonium chloride,ammonium nitrate, magnesium chloride, magnesium nitrate, calciumchloride, calcium bromide, calcium nitrate, calcium sulfate, strontiumchloride, strontium nitrate and zinc chloride.
 14. The composition ofclaim 12, which is in the form of a powder.
 15. The composition of claim12, which is in the form of a semi-solid or fluid.
 16. The compositionof claim 15, further comprising a substantially anhydrous liquidvehicle.
 17. The composition of claim 15, further comprising a glycol.18. The composition of claim 12, further comprising a surfactant.
 19. Akit for ectoparasite removal, comprising a container having therein thecomposition of claim 12, together with a device for mechanicallyremoving dead or immobile ectoparasites and their eggs.
 20. The kit ofclaim 19, wherein the device is a delousing comb.